bool SimpSMTSolver::asymm(Var v, Clause& c)
{
assert(decisionLevel() == 0);
if (c.mark() || satisfied(c)) return true;
trail_lim.push(trail.size());
Lit l = lit_Undef;
for (int i = 0; i < c.size(); i++)
if (var(c[i]) != v && value(c[i]) != l_False)
{
uncheckedEnqueue(~c[i]);
}
else
l = c[i];
if (propagate() != NULL){
cancelUntil(0);
asymm_lits++;
if (!strengthenClause(c, l))
return false;
}else
cancelUntil(0);
return true;
}
// Backward subsumption + backward subsumption resolution
bool SimpSolver::backwardSubsumptionCheck(bool verbose)
{
int cnt = 0;
int subsumed = 0;
int deleted_literals = 0;
assert(decisionLevel() == 0);
while (subsumption_queue.size() > 0 || bwdsub_assigns < trail.size()){
// Check top-level assignments by creating a dummy clause and placing it in the queue:
if (subsumption_queue.size() == 0 && bwdsub_assigns < trail.size()){
Lit l = trail[bwdsub_assigns++];
(*bwdsub_tmpunit)[0] = l;
bwdsub_tmpunit->calcAbstraction();
assert(bwdsub_tmpunit->mark() == 0);
subsumption_queue.insert(bwdsub_tmpunit); }
Clause& c = *subsumption_queue.peek(); subsumption_queue.pop();
if (c.mark()) continue;
if (verbose && verbosity >= 2 && cnt++ % 1000 == 0)
reportf("subsumption left: %10d (%10d subsumed, %10d deleted literals)\r", subsumption_queue.size(), subsumed, deleted_literals);
assert(c.size() > 1 || value(c[0]) == l_True); // Unit-clauses should have been propagated before this point.
// Find best variable to scan:
Var best = var(c[0]);
for (int i = 1; i < c.size(); i++)
if (occurs[var(c[i])].size() < occurs[best].size())
best = var(c[i]);
// Search all candidates:
vec<Clause*>& _cs = getOccurs(best);
Clause** cs = (Clause**)_cs;
for (int j = 0; j < _cs.size(); j++)
if (c.mark())
break;
else if (!cs[j]->mark() && cs[j] != &c){
Lit l = c.subsumes(*cs[j]);
if (l == lit_Undef)
subsumed++, removeClause(*cs[j]);
else if (l != lit_Error){
deleted_literals++;
if (!strengthenClause(*cs[j], ~l))
return false;
// Did current candidate get deleted from cs? Then check candidate at index j again:
if (var(l) == best)
j--;
}
}
}
return true;
}
